 |
| Phylum Porifera |
|
| |
 Primitive multicellular animals with cellular grade of organisation. |
| |
 Free living aquatic, mostly marine, sedentary forms either solitary or colonial. |
| |
 Body with a large number of incurrent pores called ostia leading into a spongocoel through a system of canals, Spongocoel opening out by one or two large excurrent pores called oscula. |
| |
 Canals and spongocoel are lined by flagellated cells called choanocytes or collar cells. |
| |
 Body wall with two layers of loosely arranged cells and a mesenchyme in between. |
| |
 Body has an endoskeleton made up of spicules. Composed of calcareous or silicious spicules or spongin fibres. |
| |
 Digestion is intracellular. |
| |
 Respiration and excretion by simple diffusion. |
| |
 Reproduction by asexual (external or internal buds) or sexual methods. |
| |
 |
| |
| fig. 10.5 - Some Common Sponges |
| |
| The phylum is divided into three classes. |
| |
 |
| |
 |
| |
| fig. 10.6 - Generalised Sponge Anatomy |
| |
